Singlet fission is usually the only reaction channel for excited states in rubrene-based organic light-emitting diodes (OLEDs) at ambient temperature. Intriguingly, we discover that triplet fusion (TF) and intersystem crossing (ISC) within rubrene-based devices begin at moderate and high current densities (j), respectively. Both processes enhance with decreasing temperature. This behavior is discovered by analyzing the magneto-electroluminescence curves of the devices. The j-dependent magneto-conductance, measured at ambient temperature indicates that spin mixing within polaron pairs that are generated by triplet-charge annihilation (TQA) causes the occurrence of ISC, while the high concentrations of triplets are responsible for generating TF. Additionally, the reduction in exciton formation and the elevated TQA with decreasing temperature may contribute to the enhanced ISC at low temperatures. This work provides considerable insight into the different mechanisms that occur when a high density of excited states exist in rubrene and reasonable reasons for the absence of EL efficiency roll-off in rubrene-based OLEDs.

Using the fingerprint magneto-electroluminescence trace, we observe a fascinating high-level reverse intersystem crossing (HL-RISC) in rubrene-doped organic light-emitting diodes (OLEDs). This HL-RISC is achieved from high-lying triplet states (T2,rub) transferred from host triplet states by the Dexter energy transfer to the lowest singlet states (S1,rub) in rubrene. Although HL-RISC decreases with bias current, it increases with lowering temperature. This is contrary to the temperature-dependent RISC from conventional thermally activated delayed fluorescence, because HL-RISC is an exothermic process instead. Moreover, owing to the competition of exciton energy transfer with direct charge trap, HL-RISC changes nonmonotonically with the dopant concentration and increases luminous efficiency to a maximum at 10% of rubrene, which is about ten times greater than that from the pure-rubrene device. Additionally, the HL-RISC process is not observed in bare rubrene-doped films because of the absence of T2,rub. Our findings pave the way for designing highly efficient orange fluorescent OLEDs.

The introduction of chiral organic ligands into hybrid organic-inorganic perovskites (HOIPs) results in chiral perovskites, which exhibit natural optical activities (NOA) such as circular polarized luminescence (CPL). CPL can be...

The data that support the findings of this study are available from the corresponding author upon reasonable request.

Owing to the presence of heavy elements such as lead (Pb) and iodine (I) in lead halide perovskites, they are known to have relatively stronger spin-orbit coupling (SOC). [7] Electronic structures of OIHPs exhibit the nondegenerated energy splitting for conduction bands. The interior crystalline inversion symmetrybreaking field leads to the spin degeneracy in term of Rashba effect mainly for the conduction bands. [8,9] Their giant dielectric permittivities help to generate Wannier-Mott excitons with low binding energies ranging from 37 to 98 meV. [10] This causes efficient dissociation of exciton in several picoseconds at room temperature. At present, intensive studies are concerned with the electronic charge and ion transport behaviors for OIHPs. [11,12] In order to fully emerge their potentials, using spin as an information carrier/bit can be a promising field for future optospintronics, nano-, and quantum electronics. [13,14] By far, spin related phenomena for OIHPs have been studied via measurements of magnetic field effects (MFEs) and spin-polarized electronic transport. [15][16][17][18][19] The formation of the ferromagnet/ perovskite spinterface such as Ni/MAPbI 3−x Cl x and Co/ MAPbI 3−x Cl x are known to have remarkable impact on magnetoresistance (MR) and magnetodielectric responses. [17,20] The hybrid interface can be also useful for generating spin-hall and inverse spin-hall effects. [21,22] Indeed, the nonmagnetic OIHPs can produce intrinsic MFEs in forms of magnetophotocurrent (MPC) and magnetophotoluminescence (MPL) even at room temperature. [15,16] The effects usually do not require ferromagnets and stem from the disturbance of spin-statistics such as singlets and triplets. Importantly, they were applied for revealing the internal spin dynamics at excited states for OIHPbased solar cells and light emitting devices. [15,16,23,24] On the other hand, an intriguing question may arise, to which extend, MFEs can be affected by ferromagnetic electrodes and the ferromagnet/perovskite spinterfaces.Herein, we have fabricated prototypical perovskite spin valves (PeSVs) with vertical structures comprising Ni/MAPbI 3−x Cl x / Ni and Ni/(PEA) 2 (MA) 3 Pb 4 I 13 /Ni. Both MAPbI 3−x Cl x and (PEA) 2 (MA) 3 Pb 4 I 13 are chemically processed based on our early experiences. [25,26] It produces rational MR even at room temperature. The signal is highly determined by the magnetic coupling of the two spinterfaces. With the same spintronic device configuration, the magnetophotocurrent at the short circuit Spinterfaces are due to the orbital hybridization at an interface of a ferromagnet and a nonmagnetic semiconductor. Interfacial densities of states (i-DOS) are spin-dependent, which may offer the spin-filter effect for enhancing spin-polarized charge injection efficiency and magnetic field effects (MFEs). In the work, a prototypical perovskite spin valve (PeSV) comprising Ni/MAPbI 3−x Cl x /Ni (MA = CH 3 NH 3 ) is fabricated, showing a clear magnetic switching behavior in the ambient condition. It is further explored ...